DE102005004380B4 - Linear motor with force ripple compensation - Google Patents

Abstract

Linear motor with the following features: - at least one primary part (13) and at least one secondary part (5), - the at least one secondary part (5) has a sequence of exciter poles with the pole pitch τM, - the length of the at least one secondary part (5) in The direction of movement of the linear motor is greater than the length of the at least one primary part (13), - the at least one primary part (13) has primary part grooves (16) with the groove pitch τN, which are provided to accommodate single or multi-phase windings - The at least one primary part (13) is formed from a laminated core (1) and has means for reducing the force ripple on its respective end faces, with a force ripple compensation (KWA) tooth (2) with a width bKWA through an air gap δKWA in addition is spaced apart from the normal air gap δL and has a distance τKWA from the adjacent wound teeth (17, 18) of the laminated core (1), characterized in that the laminated core (1) de s at least one ...

Description

The invention relates to a linear motor having at least one primary part and at least one secondary part, wherein the secondary part has a series of poles formed by permanent magnets.

Electrical machines, in particular synchronous motors, which are used as servo motors, should have the most uniform and trouble-free torque development. In rotary synchronous motors comes as a cause of periodic force fluctuations called force ripple, essentially the grooves of the stator into consideration. To compensate for this force ripple, as well as all other caused by the Nutung effects on the torque at the drive shaft usually the rotor and / or stator poles are skewed over the axial length of a groove.

For linear motors, it is z. B. from the US 4 908 533 A known to slant the poles over the width of a groove of the wound primary to reduce the force ripple. Since the edges of the end faces of the primary part in plan view run parallel to the grooves, results in the known groove bevel a bevel at the front and rear end edges of these poles.

From the EP 0 334 645 A1 It is known to reduce the force ripple in which the core of the primary part of a synchronous linear motor is formed as a ferromagnetic plate and coils are arranged in the air gap of the linear motor so that the end portions of the plate protrude beyond the Luftspaltspulen and form a step in the region of the longitudinal center line of the linear motor ,

Furthermore, from the US 4,912,746 A a linear motor is known whose teeth may be variously pronounced in the region of the end faces in order to reduce the force ripple.

From the JP 09074733 A a linear motor known whose primary part has a growing toward the end faces of its laminated core over a plurality of slots air gap.

From the DE 198 29 052 C1 a synchronous linear motor is known in which by means of variable air gap approaches to the end faces of the laminated core, the power ripple is reduced.

A linear motor having the features according to the preamble of claim 1 is known from JP 2003/199319 A known.

From the EP 1 283 586 A1 a linear motor with a relative to the primary part longer secondary part is known in which at the respective end faces in each case a Kraftwelligkeitsausgleichszahn is formed, which is spaced over a greater distance from the secondary part than the other teeth of the primary part.

From the JP 2002/209371 A is an influence of the force ripple in a linear motor by rounding the wound teeth known.

From the WO 2004/112224 A1 the reduction of locking forces in a linear motor by wedge-shaped end teeth is known.

From the DE 32 46 064 A1 It is known to extend the outer parts of the pole pieces of the end-side end poles for the suppression of disturbing reluctance forces in linear motors.

From the JP 63 077370 A It is known to attach an auxiliary coil to the end tooth of a primary part of a linear motor in order to realize the function of a position detector.

The disadvantage here is the construction and assembly costs with partially insufficient reduction of Kraftwelligkeit. This continues to occur vibrations and a restless running of the electric machine.

Proceeding from this, the object of the invention is to improve the reduction of force ripple in a synchronous linear motor with reduced design and assembly costs.

The solution of the problem is achieved by a linear motor with the features of claim 1.

The KWA tooth is thus preferably positioned in the grid of the magnetic separation τ _{M of} the secondary part to the last winding-carrying tooth. Thus, in conjunction with a suitable design of b _KWA and δ _KMA, the magnetic flux can be selectively increased. As a result, the induced voltage is raised in the winding-carrying end teeth of the primary part and at the same time significantly reduces the resulting latching forces of the synchronous linear motor.

According to the invention this leads to a relatively lower force ripple in linear motors and thus to a higher positioning accuracy. Due to the higher control quality of the synchronous linear drive thus a greater dynamics of the linear motor is achieved.

The KWA tooth or auxiliary tooth in the end region of the laminated core of the primary part is positioned in such a way that its center axis is preferably spaced by a magnetic pitch .tau. _M distance from the central axis of the has last wound tooth. As a result, the useful flow of the last wound tooth is reinforced and achieved a balanced force.

For a space-optimized design of the linear motor according to the invention τ _KWA smaller τ _M and a minimum width of the KWA tooth is sought. In order to supply the necessary net flow to the adjacent winding coils, the air gap δ _{KWA of} the KWA tooth must be reduced, but in any case greater than zero.

Due to the geometric design of the tooth and the distance to the secondary part through the additional air gap δ _KWA the influence on the induced voltage and the detent force is taken directly. Thus, the active and passive force ripples can be almost completely eliminated. This succeeds in the other embodiments, even if the windings are designed as tooth coils, each comprising only one tooth of the laminated core.

The primary part of a linear motor can consist of a plurality of laminated cores arranged one behind the other in the direction of movement. Accordingly, the centrally arranged laminated cores do not have a KWA tooth but according to the invention only KWA teeth are provided at the respective ends, that is to say the end faces of the primary part.

For primary parts with only one laminated core, ie one-piece primary parts, KWA teeth should be provided at each end.

However, this would mean for the storage of the respective primary parts that sheets without KWA tooth, with both sides KWA tooth and plates with left or right side existing KWA tooth are provided. Therefore, only two differently shaped sheets of a primary part are now provided according to the invention. Namely plates without KWA tooth and plates with left or right-sided KWA tooth.

The one-piece primary parts are now constructed so that z. B. only every other sheet has a KWA tooth on the right side and every other sheet to offset on the left side. Ie. Each plate has only one KWA tooth, which is once aligned to the left or to the right. The force ripple is thus sufficiently reduced compared to the previously known possibilities for Kraftwelligkeitsreduktion.

For primary parts with several laminated cores, sheets without KWA tooth and sheet metal with KWA tooth must be provided on the front sides. By turning a sheet with right-sided KWA tooth becomes a sheet metal with left-sided KWA tooth, so that on the front sides of these primary parts gapless KWA teeth are present.

The invention and further advantageous embodiments of the invention according to features of the subclaims are explained in more detail below with reference to schematically illustrated embodiments; show:

1 a linear motor with KWA teeth,

2 . 3 Cutouts of a primary part,

4 a method of attachment of the KWA tooth,

5 another embodiment of a KWA tooth.

1 shows a side view of a synchronous linear motor shown in principle, the one or more laminated cores 1 has, whose respective sheets are layered parallel to the drawing plane and a primary part 13 form. The direction of movement of the synchronous linear motor is indicated by arrows. The primary part 13 also has a winding system, which in the present case of tooth coils 14 is formed, ie it encloses a tooth coil 14 one tooth each 15 , so that in a groove 16 two halves of different tooth coils 14 are located. Preferably, these halves are in the primary part 13 executed almost identical, which z. B. the number of turns of the tooth coil 14 and the copper fill factor.

Of course, in another embodiment, every other tooth can 15 with a correspondingly sized tooth coil 14 be filled, so that equal copper fill factors result.

The front sides of the primary part 13 each have a KWA tooth 2 on, the distance δ _KWA to the actual air gap δ _{L of} the linear motor between the primary part 13 and abutment 5 having. The primary part 13 is over a secondary part 5 arranged on a machine bed, not shown 3 is positioned. It has permanent magnets among other things 4 with a pole pitch τ _M. The pole pitch τ _M can also be due to electrical excitation in the secondary part 5 form arranged excitation winding.

The primary part 13 of the linear motor, can be made of several individually assembled laminated cores 1 be constructed, wherein on the end faces of the primary part 13 in the direction of movement, the KWA teeth 2 are to be provided, inter alia, to achieve a higher positioning accuracy of the linear motor.

Accordingly, have the centrally arranged laminated cores 1 no KWA tooth 2 but it is according to the invention only KWA teeth 2 at the respective ends, ie the end faces of the primary part 13 provided.

At Frimärteilen 13 with only one laminated core 1 , so one-piece primary parts 13 are at each end so on the front pages KWA teeth 2 provided. The one-piece primary parts 13 are now constructed so that z. B. only every other sheet a KWA tooth 2 on the right side and every other sheet metal on the left side displaces a KWA tooth 2 having. Ie. every sheet has only one KWA tooth 2 on, which is once aligned to the left or to the right.

Due to the inventive design of the primary part 13 A linear motor is characterized by the magnetic interaction between the exciter poles and the primary part 13 caused cogging forces, which are also referred to as Cogging Force significantly reduced.

It also reduces the current-dependent force ripple, which is also referred to as Pulsating Force by now the linear motor has a symmetrically induced voltage. This is achieved by the toothed coils located on the front sides 14 now about the KWA teeth 2 have a magnetic return.

2 and 3 show various embodiments of the primary parts 13 , in particular the forms of their ends in the direction of movement. 3 is compared to the embodiment space-optimized, since almost no unused space between the last tooth coil 14 and the KWA tooth is present.

In detail, therefore, δ _{KWA, 2 is} smaller than δ _{KWA, 1} ; b _{KWA, 2} is smaller than b _{KWA, 1} and τ _{KWA, 2} is smaller than τ _{KWA, 1} .

4 shows that the KWA tooth 2 not necessarily in one piece with the laminated core 1 must be connected. It is advantageously by suitable mechanical connections such. B. dovetail joints 10 attached to the laminated core. The now between laminated core 1 and KWA tooth 2 existing minimum air gap 19 , reduces the effectiveness of the KWA tooth 2 only insignificant.

5 shows in a further advantageous embodiment of the primary part 13 a KWA tooth 2 with recesses, which are also unilateral, or symmetrical to the longitudinal axis of the KWA tooth 2 can be trained. The recess 11 , Especially when it is designed waisted, serves to receive an auxiliary coil 12 , z. B. for a boost operation by the auxiliary coil 12 with the main winding so the dental coils 14 is switched so that specific influence on the induced voltage can be taken. This additional power can be provided. The recesses 11 are also orZusätzlich suitable for receiving sensors and possibly their evaluation.

The KWA tooth 2 at one end of the primary part 13 can also be about the width of the laminated core 1 be executed differently in one or more of the following parameters: width b _{KWA of} the KWA tooth 2 , Air gap δ _{KWA of} the KWA tooth 2 and distance τ _KWA to the adjacent wound tooth 17 . 18 ,

Claims (9)

Linear motor with the following features: - at least one primary part ( 13 ) and at least one secondary part ( 5 ), - the at least one secondary part ( 5 ) has a sequence of excitation poles with the pole pitch τ _M , - the length of the at least one secondary part ( 5 ) in the direction of movement of the linear motor is greater than the length of the at least one primary part ( 13 ), - the at least one primary part ( 13 ) has primary part grooves ( 16 ), with the slot pitch τ _N , which are provided for receiving single- or multi-phase windings, - the at least one primary part ( 13 ) is made of a laminated core ( 1 ), and has at its respective end faces means for reducing the force ripple, wherein a force ripple compensation (KWA) tooth ( 2 ) having a width b _KWA is additionally spaced from the normal air gap δ _L by an air gap δ _KWA and to the adjacent wound teeth ( 17 . 18 ) of the laminated core ( 1 ) has a distance τ _KWA , characterized in that the laminated core ( 1 ) of the at least one primary part ( 13 ) has a plurality of sheets, each sheet only one KWA tooth ( 2 ), which is once aligned to the left or to the right, such that only every second sheet a KWA tooth ( 2 ) on the right side and every second plate on the left side displaces a KWA tooth ( 2 ) having. Linear motor according to claim 1, characterized in that the distance τ _{KWA of} the KWA tooth ( 2 ) to the adjacent wound tooth ( 17 . 18 ) of the laminated core ( 1 ) lies between τ _KWA = (τN + b _KWA ) / 2 and τ _KWA = τ _M Linear motor according to claim 1 or 2, characterized in that the width of the KWA tooth ( 2 ) is between δ _L and δ _M. Linear motor according to one of the preceding claims, characterized in that the air gap surface facing surface of the KWA tooth ( 2 ) runs parallel to the air gap surface. Linear motor according to one of the preceding claims, characterized in that the air gap δ _L facing corners of the KWA tooth ( 2 ) are rounded with a predetermined radius. Linear motor according to one of the preceding claims, characterized in that the windings as tooth coils ( 14 ) are formed. Linear motor according to one of the preceding claims, characterized in that the KWA tooth ( 2 ) with its adjacent laminated core ( 1 ) is formed in one piece. Linear motor according to one of the preceding claims, characterized in that the KWA tooth ( 2 ) in its course over the thickness of the laminated core ( 1 ) is made different widths. Linear motor according to one of the preceding claims, characterized in that the KWA tooth ( 2 ) is made different width over its height.

Images